Prerequisites to Migrating a Single Directory Server Instance
From 5.2

Before migrating from a 5.2 server instance, ensure that the following
prerequisites are met:

Directory Server 6.0 must be installed.
The new server can be installed on the same machine as the existing server
or on a different machine.

Ensure that the new machine has sufficient local disk space
to house binaries and databases for both the old and new servers, and also
enough extra space to hold LDIF files containing the entries in all existing
suffixes. You can estimate the local disk space required as somewhat larger
than the following calculation.

If you are using the automatic migration tool, the following two prerequisites
must be met:

The existing server instance must be stopped cleanly.

If the new server is located on a different machine, a complete
image of the original server instance must be created on the new machine.
This includes all schema files, configuration files, security files, and database
files, in an identical layout to the original server root.

If your Directory Server deployment includes Identity Synchronization for Windows,
you must uninstall Identity Synchronization for Windows before migrating to Directory Server 6.0.
For information about migrating Identity Synchronization for Windows, see Chapter 7, Migrating Identity Synchronization for Windows.